Option[Int] function parameter impl conv. error with null??

[John K.]

[Scala 2.9.1]

I am creating a function that takes an Option[Int] as one of its parameters, as this parameter maybe null...

Here is what is happening...

scala> def nullTest(n:Option[Int]) = n.getOrElse(0)

nullTest: (n: Option[Int])Int

scala> nullTest(Option(null))

<console>:9: error: type mismatch;

 found   : Null(null)

 required: Int

Note that implicit conversions are not applicable because they are ambiguous:

 both method Integer2intNullConflict in class LowPriorityImplicits of type (x: Null)Int

 and method Integer2int in object Predef of type (x: java.lang.Integer)Int

 are possible conversion functions from Null(null) to Int

              nullTest(Option(null))

So how can i create a Option[Int] parameter that maybe null?

FYI, This does work using a String.

IE.

scala> def nullTest(n:Option[String]) = n.getOrElse("I got Nothing")

nullTest: (n: Option[String])String

scala> nullTest(Option(null))

res20: String = I got Nothing

[Rex Kerr]

Int is a primitive type, so
  val i : Int = null
doesn't exactly make sense.

I suspect that you're just trying to represent that the integer doesn't exist.  In that case, use None instead of Option[Int](null).

(None is the universal empty option.)

  --Rex

[Lanny Ripple]

You can cast null as any of the basic types

scala> def nullTest(n:Option[Int]) = n.getOrElse(0)

nullTest: (n: Option[Int])Int

scala> nullTest(Option(null.asInstanceOf[Int]))

res1: Int = 0

Note that for primitive types you'll get the "zero"

scala> null.asInstanceOf[Boolean]

res2: Boolean = false

scala> null.asInstanceOf[Char]

res3: Char = ?

scala> res3.toInt

res4: Int = 0

And for Object's you'll just get null

scala> null.asInstanceOf[String]

res5: String = null

I find it interesting that even though the zero acts correctly

scala> null.asInstanceOf[Int] + 3

res6: Int = 3

It's still a null by value

scala> Option(null.asInstanceOf[Int])

res7: Option[Int] = None